The invention relates to a knitting machine flat or circular, with a patterning arrangement. The knitting machine itself is provided with a needle carrier, flat or circular, in which knitting needle units are longitudinally reciprocable to effect knitting. The knitting needle units comprised of needle portions and motion-imparting portions which are either integral with each other, or in the form of two distinct members. The patterning arrangement of the knitting machine causes the motion-imparting members to be selectively moved either to operative positions in which they are moved by lifting and lowering cams, or else to an inoperative position in which they are not so moved by the lifting and lowering cams.
More particularly, the invention relates to needle selecting arrangements for knitting machines, of the type wherein the needle selection is effected by energizing or deenergizing control members comprised of materials which undergo dimensional changes, for example piezoelectric, electrostrictive, magnetostrictive, or bimetallic control members, and the like, in contradistinction to the older and more familiar use of electromagnetic relays for this purpose.
It has already been proposed (in West German published Pat. applications Nos. 1,804,350 and 2,115,332) to replace the electromagnetic needle selector arrangements of known patterning arrangements, such as are almost universally employed in knitting machines now being manufactured, with piezoelectric members which bend and straighten in response to the application thereto of electrical energizing signals. This bending and straightening is to be understood to be comprehended within the meaning of the term "dimensional change", employed herein.
The piezoelectric or other control members can be so configurated and disposed as to effect a needle selecting operation. The great advantage of the use of piezoelectric control members, and the like, resides in that they can be alternately activated and deactivated with a very high frequency, and in that they undergo the dimensional changes with extreme quickness and little or no sluggishness or time lag. Also, in comparison to the electromagnets employed in conventional needle-selecting arrangements, they are of relatively small size. A disadvantage of the use of piezoelectric members and the like is that the actual force which they directly bring to bear is not great, compared for example to the force which can be exerted by an electromechanical relay. However, this limitation can be overcome by exploiting the combined action of a plurality of such piezoelectric control members, or the like, and/or by making use of such control members in needle-selecting arrangements where the control members are not called upon to create the actual force which moves the motion-imparting portions of the needle units into and out of engagement with the lifting and lowering cams.